The present invention concerns intermediate compounds useful in the preparation of N-[2-(carboxymethoxy)ethyl]-N-(carboxymethyl)glycine (CMHEIDA), also referred to as carboxymethoxyhydroxyethylimino diacetic acid.
Chelants or chelating agents are compounds which form coordinate-covalent bonds with a metal ion to form chelates. Chelates are coordination compounds in which a central metal atom is bonded to two or more other atoms in at least one other molecule or ion, called a ligand, such that at least one heterocyclic ring is formed with the metal atom as part of each ring.
Chelating agents for metal ions, such as calcium, magnesium, iron, and magnesium, are required for a wide range of technical fields. Examples of fields of application and end-uses of chelants are detergents, in electroplating, in water treatment, photography, textile industry, paper industry and also various uses in pharmaceuticals, cosmetics, foodstuffs and plant nutrition. Some of these activities may result in the chelating agents entering the environment. For example, agricultural uses or use in detergents may result in measurable quantities of the chelants in water.
As chelants many enter the environment from various uses, it is desirable to have chelants that would readily degrade after use. It would be particularly advantageous to have a chelant which is biodegradable, that is, susceptible to degradation by microbes which are generally naturally present in environments into which the chelants may be introduced.
Iminodiacetic acid derivatives are known to possess metal sequestering properties. US patent 5,051,212 discloses that iminodiacetic acid derivatives, when combined with organic solvents, provide very good results in terms of soil removal from hard surfaces. The use of iminodiacetic acid derivatives in aqueous compositions for cleaning hard surfaces is reported in PCT Application No. WO 94/12606. The iminodiacetic acid derivatives in WO 94/12606 are also reported to have good biodegradable characteristics.